Integrated circuit package including opening exposing portion of an IC

ABSTRACT

An IC package preferably includes an IC and encapsulating material surrounding the IC, with the encapsulating material having an opening therein to define an exposed portion of the IC. Vestigial portions of encapsulating material may be left on the exposed portion of the IC and spaced inwardly from a periphery of the opening based upon molding using a mold protrusion which includes a bleed-through retention channel positioned inwardly from peripheral edges. The channel collects and retains any bleed-through of the encapsulating material. The IC package may further include a leadframe carrying the IC. The leadframe may include a die pad, finger portions, and a plurality of die pad support bars. The die pad may be downset below a level of the finger portions. Each of the die pad support bars may be resiliently deformed to accommodate the downset of the die pad. Low stress encapsulating material and adhesive may also be included in the IC package.

RELATED APPLICATION

This application is based upon U.S. provisional application serial No.60/225,972 filed Aug. 17, 2000, the entire contents of which areincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to the field of electronics, and, moreparticularly, to integrated circuit packages.

BACKGROUND OF THE INVENTION

Integrated circuit (IC) devices or packages are used in a wide varietyof electronic applications including computers, cellular telephones,entertainment systems, etc. A typical IC package includes a chip ofsemiconductor material, or IC, in which active electronic devices areformed. Surrounding the IC is an encapsulating material, such astypically formed of a thermosetting or thermoplastic resin compound. Toprotect the IC from damage or contamination, the encapsulating materialtypically totally surrounds the IC.

The IC itself may be carried by a leadframe. The leadframe includes adie pad which carries the IC, finger portions which provide theelectrical pins extending outwardly from the encapsulating material, anddie pad support bars which extend from the die pad to the fingerportions. Contact or bond pads on the surface of the IC are typicallyelectrically connected to respective finger portions by bond wires whichare surrounded by encapsulating material.

IC packaging has typically been concerned with protection andinterconnects. Low cost, high volume manufacturing techniques are wellestablished for conventional IC packaging. However, with the advent ofvarious types of sensor, receiving, and/or transmitting circuits basedon IC's, the need has arisen to expose some or most of the surface ofthe IC to the ambient environment. An example of such an IC device is anelectric field fingerprint sensor, such as of the type described in U.S.Pat. No. 5,963,679 to Setlak and U.S. Pat. No. 5,862,248 to Salatino etal. Such sensors are available commercially from the assignee of thesepatents and the present invention, AuthenTec, Inc. of Melbourne, Fla.

The Salatino et al. patent, for example, discloses several approachesfor molding the opening in the encapsulating material to expose thefingerprint sensing matrix. One approach uses a frame which holds a bodyof removable material in its interior and which is positioned on the ICbefore molding. After molding the body may be removed thereby producingthe opening through the encapsulating material. In another embodiment,an upper mold includes a downward protruding portion which directlycontacts the IC to exclude the encapsulating material from the surfaceof the IC during injection molding to thereby form the opening exposingthe IC.

Somewhat similar, a number of other patents disclose forming an openingin the encapsulating material from beneath the IC. Accordingly, coolingmedia may be circulated in the opening, such as disclosed in U.S. Pat.No. 5,687,474 to Hamzehdoost et al. Similarly, U.S. Pat. No. 5,570,272to Variot provides a heatsink body in the opening beneath the IC. Apressure sensor is disclosed in U.S. Pat. No. 5,424,249 to Ishibashiwherein the encapsulating material is first completely formed then anopening is cut therethrough to an underlying sensing diaphragm.

Methods for packaging IC's with an opening therein have generally beencumbersome and expensive, such as requiring specialized pre-madepackaging and flexible or rigid printed circuit boards. These approachesare not well-suited to reliable, high volume, low cost manufacturing.Indeed, despite continuing significant developments, such as thosedescribed in the above noted Salatino et al. patent, a number ofchallenges are still presented for an IC package that exposes a portionof the IC. For example, it may be difficult to keep encapsulatingmaterial from bleeding under a mold protrusion that contacts the IC toform the opening. Preventing crush damage to the IC from foreignparticles pressed between the mold and the IC also remains a challenge.Variations in the thicknesses of the IC's, adhesive layers, leadframes,etc. as well as accommodating IC skew also remains an area of concern.

SUMMARY OF THE INVENTION

In view of the foregoing background, it is therefore an object of theinvention to provide an integrated circuit package comprising an IC andencapsulating material surrounding the IC, but leaving an exposedportion, and wherein the IC package is readily manufactured.

This and other objects, features, and advantages in accordance with thepresent invention are provided by an integrated circuit packagecomprising an IC and encapsulating material surrounding the IC, with theencapsulating material having an opening therein to define an exposedportion of the IC. In one class of embodiments, in view of themanufacturing approach, vestigial portions of encapsulating material areleft on the exposed portion of the IC and spaced inwardly from aperiphery of the opening in the encapsulating material. This is a resultof a manufacturing process using a mold protrusion to form the opening.The mold protrusion may include a bleed-through retention channelpositioned inwardly from the peripheral edges of an IC-contact surface.The bleed-through retention channel collects and retains anybleed-through of the encapsulating material and prevents its spreadfurther inwardly onto the exposed surface of the IC.

The opening in the encapsulating material may be generally rectangular.Accordingly, the vestigial portions of encapsulating material may bearranged along at least one side of an imaginary rectangle spacedinwardly from the generally rectangular opening in the encapsulatingmaterial.

In some embodiments, the IC package may further include a leadframecarrying the IC. More particularly, the leadframe may comprise a diepad, finger portions, and a plurality of die pad support bars extendingbetween the die pad and the finger portions at the corners. The die padmay be downset below a level of the finger portions. In addition, eachof the die pad support bars may be resilient deformed to accommodate thedownset of the die pad.

The package may further include bond wires extending between the IC andthe finger portions. These bond wires may have a desired clearance fromadjacent portions of the IC and an upper surface of the encapsulatingmaterial when the die pad is downset. In other words, shaping of thebond wires is performed to account for the downset imparted duringmanufacturing.

To reduce stress during cooling, the die pad may have an openingtherein. Further, a low stress, low modulus adhesive may be used tosecure the IC to the die pad. The encapsulating material may also be alow stress encapsulating material.

In other embodiments, the IC package may include a substrate on a backsurface of the IC opposite the exposed portion. This substrate may coverthe back surface so that the encapsulating material does not extend ontothe back surface. In slightly different terms, the substrate, such as aprinted circuit board, provides protection for the back surface of theIC and becomes part of the package.

The IC may include upper surface portions with active devices formedtherein. The exposed portion of the IC may comprise these upper surfaceportions. In some advantageous embodiments, the active devices maydefine a sensor, such as an electric field fingerprint sensor, forexample. Other devices may be similarly packaged.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an exemplary fingerprint sensor ICpackage in accordance with the present invention.

FIG. 2 is a schematic cross-sectional view of the IC package as shown inFIG. 1 during manufacture.

FIG. 3 is an enlarged plan view of a portion of the leadframe as shownin FIG. 2.

FIGS. 4 and 5 are schematic partial side cross-sectional views duringmanufacture of the IC package as shown in FIG. 1.

FIG. 6 is a greatly enlarged schematic partial side cross-sectional viewof the IC package during manufacture thereof after encapsulatingmaterial has been injected into the mold.

FIG. 7 is a flowchart of the method for manufacturing the IC package asshown in FIG. 1.

FIGS. 8 and 9 are schematic cross-sectional views of another embodimentof an IC package during manufacturing thereof.

FIG. 10 is a perspective view of the IC package as shown in FIGS. 8 and9 upon completion.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be described more fully hereinafter withreference to the accompanying drawings, in which preferred embodimentsof the invention are shown. This invention may, however, be embodied inmany different forms and should not be construed as limited to theembodiments set forth herein. Rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art. Likenumbers refer to like elements throughout.

For clarity of explanation, the present invention is explained withreference to manufacturing methods for making an IC package 30 in theillustrated form of an electric field fingerprint sensor IC package asshown in FIG. 1. The electric field fingerprint sensor IC package 30 mayof the type using an electric field to sense the ridges and valleys of afingerprint as offered by AuthenTec, Inc. of Melbourne, Fla. under thedesignation FingerLoc™ AF-S2™.

The IC package 30 illustratively corresponds to a JEDEC-standard 68-pinplastic leaded chip carrier (PLCC) format, although other sizes,standards, and configurations are possible. The IC package 30 may beabout 24 mm square, and have a height or thickness of about 3.5 mm, forexample. Another exemplary package may be a 144 lead LQFP about 1.6 mmthick.

Further details on the operation of the electric field fingerprintsensor may be found in U.S. Pat. Nos. 5,963,679 and 5,862,248 mentionedabove, and, the entire disclosures of which are incorporated herein byreference. Of course, other sensors and other devices are alsocontemplated by the present invention.

The IC package 30 illustratively includes an IC chip or die 32illustratively including an IC sensor matrix 31 which is exposed throughan opening 36 in the upper portion of the encapsulating material 33.Vestigial portions of encapsulating material may remain on the exposedportion of the IC 32, outside the area of the sensor matrix 31. Thesevestigial portions 39 are schematically indicated in FIG. 1 by thedashed line rectangle and these vestigial portions are described ingreater detail below.

The IC package 30 also includes a leadframe on which the IC 32 ismounted as will be described in greater detail below. The leadframeincludes a plurality of finger portions which become the visible leadsor pins 37 which also extend outwardly from the sides of theencapsulating material 33 as will be appreciated by those of skill inthe art. An annular drive ring 34 is provided on the upper surface ofthe encapsulating material 33 adjacent the opening 36 exposing thesensing matrix 31. This drive ring 34 is specific to the illustratedelectric field fingerprint sensor and is not needed in all suchembodiments, or in other IC packages.

For ease of explanation, the term “IC” by itself is used primarilyherein for simplicity to denote the actual integrated circuit die aswill be appreciated by those of skill in the art. Also for ease ofexplanation, the term “IC package” is used to indicate the IC 32,surrounding encapsulating material 33, leadframe 35, etc. as an entity.

Referring now additionally to the flowchart 50 of FIG. 7, and theschematic diagrams of FIGS. 2 through 5, further details of themanufacturing method and IC package 30 produced thereby are nowdescribed. From the start (Block 52), an IC 32 is attached to a die pad41 of the leadframe 35 at Block 54. More particularly, as perhaps bestunderstood with reference to FIGS. 2 and 3, the leadframe 35 includes adie pad 41 and finger portions 43 which are connected together at eachcorner by a respective resilient die pad support bar 44. As will beappreciated by those skilled in the art, the finger portions 43 arelater processed to form the visible leads 37 extending outwardly fromthe encapsulating material 33 as shown in FIG. 1.

The die pad 41 of the leadframe 35 also illustratively has a centralopening 42 therein. This opening 24 reduces stress during cooling of theencapsulating material 33 as will be described in greater detail below.A low stress, low modulus adhesive 49 may also be used to adhesivelysecure the IC 32 to the die pad 41 as will also be described in greaterdetail below.

At Block 56 the bond wires 45, which extend between respective fingerportions 43 and bond pads 46 of the IC 32, are shaped to account forlater downsetting. As shown best in FIGS. 2 and 4, the bond wires 45 areinitially shaped so as to be angled downwardly at their upper ends.These upper ends will extend generally horizontally upon downsetting asshown best in FIGS. 5 and 6.

At Block 58 a mold is provided having first and second, or upper andlower mold portions 47, 48 as shown in FIG. 4. The first or upper moldportion 47 preferably carries a mold protrusion 70 defining anIC-contact surface 71 with peripheral edges and a bleed-throughretention channel 72 positioned inwardly from the peripheral edges.

At Block 60 the upper and lower mold portions 47, 48 are closed aroundthe IC 32. As shown in the illustrated embodiment, the IC-contactsurface 71 contacts and presses directly upon the upper surface of theIC 32 and causes the IC to be downset a distance DS as shown in FIG. 5.In other words, the resilient die pad support bars 44 permit the IC 32to be contacted and moved downwardly to the position as shown in FIG. 5so that the die pad 41 is displaced below the finger portions 43.Accordingly, a close fit is provided between the IC 32 and contactsurface 71 to prevent encapsulating material from bleeding extensivelybeneath the mold protrusion 70 and onto the surface of the IC 32, andwithout crushing the IC.

The downsetting also accommodates skew of the IC surface and variationsin thickness of the IC 32, adhesive layer 49, and/or portions of theleadframe 35 as will be readily appreciated by those skilled in the art.Considered in somewhat different terms, the manufacturing methodincludes controlling pressure applied by the IC-contact surface 71 tothe IC 32 when the first and second mold portions 47, 48 are closedaround the IC. This may be done as shown in the illustrated embodimentby mounting the IC 32 on the leadframe 35 having resilient portions toresiliently accommodate downsetting of the IC as the IC-contact surface71 contacts the IC. The resilient die pad support bars 44 as shown inthe illustrated embodiment, for example, maintain a desired pressureplaced on the IC 32 by the contact surface 71 of the mold protrusion 70when the mold is closed. The die pad support bars 44 are placed intension by the downsetting to provide a spring-like force or pressure toIC 32 against the contact surface 71 of the mold protrusion 70. Thispressure is controlled to avoid risk of damage while reducing likelihoodof bleed-through of the encapsulating material 33 beneath the contactsurface 71 as will be appreciated by those skilled in the art.Considered yet in other terms, the die pad 41 is essentially allowed tofloat during the molding process. The die pad support bars 44 canreadily accommodate tolerance variations of several thousandths of aninch and produce high quality IC packages.

The downsetting also aligns the bond wires 45 in a proper position toprovide clearance from adjacent portions of the IC 32 as well as toprovide clearance from the adjacent upper surface portions of theencapsulating material 33. Accordingly shorts from contact with the IC32, or bond wires 45 being exposed through the encapsulating material 33are avoided. As shown in the illustrated embodiment of FIG. 5, the bondwires 45 in the completed position after downsetting may have upperportions which extend generally horizontally away from the IC 32 beforeturning downward toward the finger portions 43 of the leadframe 35.

At Block 62 the encapsulating material 33 is injected into the mold fromthe schematically illustrated injector 75 under controlled pressure.Those of skill in the art will appreciate detailed construction andoperation of the encapsulating material injector 33 without furtherdiscussion herein.

As can be seen perhaps best in FIG. 6, a small bead or line ofencapsulating material 33 may bleed under the peripheral edges of themold protrusion 70 and remain as a vestigial portion 39 of theencapsulating material on the exposed surface of the IC 32. As will beappreciated by those skilled in the art the relative size of thevestigial portions 39 is greatly exaggerated for clarity ofillustration. In short, the bleed-through retention channel 72 retainsany encapsulating material bleeding beneath the peripheral edges of theIC contact surface 71.

It has been found that a flat contact surface of a mold protrusion aloneis not likely to reliably prevent the encapsulating material 33 fromwicking along the interface between the contact surface 71 and the IC32. It is also likely that typical mold clamping pressures cannot beexerted on the IC 32 without considerable risk of damage. Because theclamping pressure is typically lowered, the potential for bleed-throughor wicking of the encapsulating material becomes more important.Accordingly, the bleed-through retention channel 72 may be considered asproviding a moat to act as a natural break for the bleeding of theencapsulating material 33 during molding.

The mold protrusion 70 may comprise a resilient material, and have agenerally rectangular shape having a side dimension of about 5 to 20 mmfor an IC package 30 having a side dimension of about 25 mm, forexample. The bleed-through retention channel 72 may be spaced inwardlyfrom the peripheral edges a distance of about 0.2 to 0.4 mm, forexample. The retention channel 72 may also have a width of about 1 mm,and a height of about 0.15 to 0.25 mm. Those of skill in the art willappreciate that other sizes are also contemplated by the presentinvention depending on the application and the size of the IC package.

The IC package 30, that is, the IC 32, leadframe 35, and encapsulatingmaterial 33 may be released from the mold at Block 64 before stopping atBlock 66. Those of skill in the art will appreciate that other finishingsteps, including trimming excess encapsulating material, and separatingthe finger portions, for example, are also typically performed toproduce the finished IC package 30.

Another aspect of the manufacturing relates to stress relief. Stressrelief may be important since the encapsulating material 33 and the IC32 typically have different coefficients of thermal expansion (CTEs). Itis noted that the leadframe 35 may also have a different CTE.Accordingly, the manufacturing method preferably includes relievingstress during cooling of the encapsulating material 33 despite thedifferent CTEs. The IC package 30 will have an unbalance ofthermal-mechanical stress because of the opening 36. This is in contrastto the balanced stress which results in a balanced compressive forceexperienced by an IC in a typical fully encapsulated IC.

For example, relieving the stress may comprise using a low stressencapsulating material 33. For example, the encapsulating material 33may be a mold compound sold under the designation Plaskon SMT-B1-LV byCookson Semiconductor Packaging Materials of Alpharetta, Ga. Those ofskill in the art will appreciate that other similar mold compounds maybe used as well. Alternately or additionally, stress relief may beprovided by using a leadframe 35, such as illustrated and describedherein, which includes the die pad 41 with the opening 42 therein. TheIC 32 may also be mounted on the die pad 41 using a low stress, lowmodulus adhesive 49. For example, the die attach adhesive 49 may be anadhesive sold under the designation Ablebond 8340, and manufactured byAblestick Electronics Materials and Adhesives (National Starch andChemical Co.) of Rancho Dominguez, Calif. The low stress, low modulusadhesive 49 and/or open die pad 41 tends to decouple the IC 32 from theleadframe 35 which may typically comprise copper.

As described herein, the IC 32 may have an upper surface with activedevices formed therein, such as the illustrated fingerprint sensor withthe pixel element matrix 31. Of course, those of skill in the art willappreciate that the techniques described herein could also be used toexpose the back or underside of an IC.

The first and second mold portions 47, 48 may each comprise a rigidmaterial, such as hardened steel, to provide accurate dimensions and toresist abrasion from the encapsulating material 33. Although the moldingprocess is relatively clean, small particles may be left on the top ofthe IC 32 or on the contact surface 71 of the mold protrusion 70 as willbe readily appreciated by those skilled in the art. In contrast to themold portions 47, 48, the mold protrusion 70 may comprise a compliant orresilient material so that any contaminants are not forced into the IC32 causing damage. The material properties of the mold protrusion 70 aredesirably such that any small particles will be pressed into the contactsurface 71 instead of into the IC 32. However, it is still desired thatthe mold protrusion 70 retain its shape through the molding process. Themold tooling is also preferably such as to permit removal of the moldprotrusion 70 for cleaning and/or replacement if worn or damaged as willalso be appreciated by those skilled in the art.

One attribute of the molding process is that the mold will acquire abuild-up of encapsulating material and wax material that may produceaesthetic problems in the finished IC package. Accordingly, moldcleaning is typically performed at periodic intervals. A conventionalmold cleaning process entails molding a plastic gettering material, suchas melamine, that will adhere to any organic material. After a fewmolding cycles using the gettering material, normal production iscontinued. The melamine has a high adhesion to organic particles, butlow adhesion to hardened steel mold surfaces.

The mold protrusion 70 can be made of any of a number of appropriatematerials. If the mold protrusion 70 is formed of an organic polymer,precautions may be needed to clean the mold, as the conventionalmelamine cleaning process could potentially damage the compliant moldprotrusion by sticking to it and pulling it apart. Several approachesmay be used to alleviate this potential difficulty. The organic polymermold protrusion 70 can be temporarily replaced with a correspondingmetal insert during melamine cleaning, for example. A metal or non-stickcap or non-stick coating could be provided over the organic polymer moldprotrusion 70.

Returning again to FIGS. 1 through 6, it can be appreciated that the ICpackage 30 produced using the advantageous processes described hereinwill have certain distinguishing features and characteristics. Forexample, in one class of embodiments, in view of the manufacturingapproach, vestigial portions 39 of encapsulating material 33 are left onthe exposed portion 31 of the IC 32 and spaced inwardly from a peripheryof the opening 36 in the encapsulating material. Of course, thesevestigial portions 39 could be removed in some embodiments if desired,but simpler and less expensive manufacturing is obtained if thevestigial portions do not effect IC operation and are, therefore,allowed to remain on the IC 32.

As described herein, the opening 36 in the encapsulating material 33 maybe generally rectangular. For these embodiments the vestigial portions39 of encapsulating material are arranged along an imaginary rectanglespaced inwardly from the generally rectangular opening in theencapsulating material. It should be noted that the vestigial portions39 need not necessarily be connected to form a complete rectangle,rather, the vestigial portions may be spaced, but lie along an imaginaryrectangle as defined by the bleed-through retention channel 72 of themold protrusion 70. For example, the vestigial portions may be spacedinwardly a distance of from 0.1 to 3 mm for an IC package having sidedimensions of about 25 mm. Of course, the same principles can be readilyapplied to other polygonal, round, or other closed geometric shapes aswill be appreciated by those skilled in the art.

Another characteristic of the IC package 30 resulting from manufactureas described herein is the downset relationship of the die pad 41relative to the finger portions 43. The die pad support bars 44 may alsobe resiliently deformed to accommodate the downset of the die pad 41. Inaddition, the bond wires 45 will also likely have a desired clearancefrom adjacent portions of the IC 32 and an upper surface of theencapsulating material 33 when the die pad 41 is downset.

As also described herein, to reduce stress during cooling, the die pad41 (FIG. 3) may have an opening 42 therein. Further, a low stress, lowmodulus adhesive 49 may be used to secure the IC to the die pad 41. Theencapsulating material 33 may also be a low stress encapsulatingmaterial.

The IC 32 may include upper surface portions with active devices formedtherein, such as fingerprint sensing circuitry. The exposed portion ofthe IC may comprise these upper surface portions. In some advantageousembodiments, the active devices may define a sensor, such as an electricfield fingerprint sensor, for example. Other devices may be similarlypackaged as will be also readily understood by those skilled in the art.

Turning now additionally to FIGS. 8-10, another embodiment of an ICpackage 80 and its method of manufacture are now described. As shown inFIG. 8, the IC 81 is adhesively secured to a substrate 84, which may bea printed circuit board, for example. For clarity of explanation, thelayer of adhesive is not shown, but may be of the type described above,for example. The substrate 84 may be rigid in some embodiments, but canalso be flexible in other embodiments. The substrate 84 may be a ballgrid array substrate, or be of the type that with further processingwill become a ball grid array substrate. Other substrate types are alsocontemplated by the invention. In other words, in this IC package 80 theleadframe 35 for mounting the IC and described extensively above isreplaced with the substrate 84.

In the illustrated embodiment, the bond pads 82 are also along only oneside of the IC 81, and, accordingly, the bond wires 83 are also alongonly one side of the IC 81. Those of skill in the art will recognizethat in other embodiments, the bond pads 82 could be along two, three orall four sides in other embodiments.

The IC 81 and substrate 84 are placed between a lower mold portion 85and an upper mold portion 86 as shown in FIG. 9, and encapsulatingmaterial 91 is injected under controlled pressure. A mold protrusion 87is provided adjacent the upper mold portion 86. The mold protrusion 87is desirably relatively compliant so as not to crush foreign particlesinto the IC 81. Further, in this embodiment, since downsetting of aleadframe 35 is not used to accommodate variations in thicknesses, thecompliancy of the mold protrusion 87 accommodates any variations, suchas in the thickness of the substrate 84, adhesive layer and/or IC 81. Inone example, the mold protrusion 87 may comprise a solid body of Teflon,for example. As will be seen below, because there is no encapsulatingmaterial 91 injected under pressure beneath the IC 81, a more compliantmold protrusion 87 may be used than compared, for example, to theembodiments described above using the leadframe 35.

The upper mold portion 86 may be provided as two portions which mate atthe illustrated dashed line 88. In other words the upper mold portion 86may include a changeable cavity plate at the level of the dashed line 88so that this plate may be changed to accommodate different sizedpackages as will be appreciated by those skilled in the art.

In this illustrated embodiment, it is further noted that thebleed-through retention channel 90 in the mold protrusion 87 is onlyalong the right hand side of the IC 81. This is so because theencapsulating material 91 will extend onto the upper surface of the IC81 to cover the bond pads 82 and bond wires 83 on the right hand side.On the lefthand side it can be seen that the encapsulating material 91does not extend onto the upper surface, and bleed through of theencapsulating material can be controlled since the mold protrusion 87extends completely over the upper surface and slightly beyond. Those ofskill in the art will appreciate that in other embodiments, the moldprotrusion 87 could also be made or configured to have the bleed-throughretention channel 90 extend on two, three or all four sides.

The finished IC package 80 is shown in FIG. 10 wherein an upper surface92 of the IC 81 is exposed through the opening 93 in the encapsulatingmaterial 91. In this illustrated embodiment, the substrate 84 extendsoutwardly beyond the side edges of the IC 81. In other embodiments, theside edges of the substrate 84 may be terminated flush with the sideedges of the IC 81 as will be appreciated by those skilled in the art.The vestigial portions 95 of encapsulating material 91 are alsoschematically illustrated by the dashed line on the right hand side ofthe upper surface 92 of the IC 81.

It is further noted that although the encapsulating material 91surrounds the IC 81, there is no encapsulating material 91 on the backsurface of the IC in the illustrated IC package 80. In this embodiment,the substrate 84 provides the protection for the back surface.

Other aspects of the invention are disclosed in U.S. Patent ApplicationSer. No. 09/931,587, entitled “METHODS AND APPARATUS FOR MAKINGINTEGRATED CIRCUIT PACKAGE INCLUDING OPENING EXPOSING PORTION OF THE IC”file concurrently herewith. The entire contents of this application areincorporated herein by reference. In addition, many modifications andother embodiments of the invention will come to the mind of one skilledin the art having the benefit of the teachings presented in theforegoing descriptions and the associated drawings. Accordingly, it isunderstood that the invention is not to be limited to the illustratedembodiments disclosed, and that other modifications and embodiments areintended to be included within the spirit and scope of the appendedclaims.

That which is claimed is:
 1. An integrated circuit package comprising:an integrated circuit (IC) and encapsulating material surrounding saidIC, said encapsulating material having an opening therein to define anexposed portion of said IC; and vestigial portions of said encapsulatingmaterial on the exposed portion of said IC an spaced inwardly from aperiphery of the opening in maid ecapsulating material.
 2. An integratedcircuit package according to claim 1 wherein the opening in saidencapsulating material is generally rectangular; and wherein saidvestigial portions of encapsulating material are arranged along at leastone side of an imaginary rectangle spaced inwardly from the generallyrectangular opening in said encapsulating material.
 3. An integratedcircuit package according to claim 1 wherein said vestigial portions arespaced inwardly a distance of from 0.1 to 3 mm.
 4. An integrated circuitpackage according to claim 1 further comprising a leadframe carryingsaid IC.
 5. An integrated circuit package according to claim 4 whereinsaid leadframe comprises a die pad, finger portions, and a plurality ofdie pad support bars extending between said die pad and said fingerportions.
 6. An integrated circuit package according to claim 5 whereinsaid die pad is downset below a level of said finger portions.
 7. Anintegrated circuit package according to claim 6 wherein each of said diepad support bars is resiliently deformed to accommodate the downset ofsaid die pad.
 8. An integrated circuit package according to claim 6further comprising bond wires extending between said IC and the fingerportion having a desired clearance from adjacent portions of said IC andan upper surface of said encapsulating material.
 9. An integratedcircuit package according to claim 5 wherein said die pad has an openingtherein.
 10. An integrated circuit package according to claim 5 furthercomprising a low stress, low modulus adhesive securing said IC to saiddie pad.
 11. An integrated circuit package according to claim 1 furthercomprising a substrate adjacent a back surface of said IC opposite theexposed portion.
 12. An integrated circuit package according to claim 1wherein said substrate covers the back surface of said IC so that saidencapsulating material does not extend onto the back surface.
 13. Anintegrated circuit package according to claim 1 wherein saidencapsulating material comprises a low stress encapsulating material.14. An integrated circuit package according to claim 1 wherein said ICcomprises upper surface portions with active devices formed therein; andwherein the exposed portion of said IC comprises upper surface portionsthereof.
 15. An integrated circuit package according to claim 14 whereinthe active devices define a sensor.
 16. An integrated circuit packageaccording to claim 14 wherein the active devices define an electricfield fingerprint sensor.
 17. An integrated circuit package comprising:an integrated circuit (IC) comprising upper surface portions with activedevices formed therein and encapsulating material surrounding said IC;said encapsulating material having an opening therein adjacent the uppersurface portions of said IC to define an exposed portion of said IC; anda leadframe comprising a die pad carrying said IC, finger portions, anda plurality of die pad support bars extending between said die pad andsaid finger portions; said die pad being downset below a level of saidfinger portions.
 18. An integrated circuit package according to claim 17wherein each of said die pad support bars is resiliently deformed toaccommodate the downset of said die pad.
 19. An integrated circuitpackage according to claim 18 further comprising bond wires extendingbetween said IC and the finger portion having a desired clearance fromadjacent portions of said IC and an upper surface of said encapsulatingmaterial.
 20. An integrated circuit package according to claim 17wherein said die pad has an opening therein.
 21. An integrated circuitpackage according to claim 20 further comprising a low stress, lowmodulus adhesive securing said IC to said die pad.
 22. An integratedcircuit package according to claim 17 wherein said encapsulatingmaterial comprises a low stress encapsulating material.
 23. Anintegrated circuit package according to claim 17 further comprisingvestigial portions of encapsulating material on the exposed portion ofsaid IC and spaced inwardly from a periphery of the opening in saidencapsulating material.
 24. An integrated circuit package according toclaim 23 wherein the opening in said encapsulating material is generallyrectangular; and wherein said vestigial portions of encapsulatingmaterial are arranged along an imaginary rectangle spaced inwardly fromthe generally rectangular opening in said encapsulating material.
 25. Anintegrated circuit package according to claim 23 wherein said vestigialportions are spaced inwardly a distance of from 0.1 to 3 mm.
 26. Anintegrated circuit package according to claim 17 wherein the activedevices define a sensor.
 27. An integrated circuit package according toclaim 17 wherein the active devices define an electric field fingerprintsensor.
 28. An integrated circuit package comprising: an integratedcircuit (IC) comprising upper surface portions with active devicesformed therein and encapsulating material surrounding said IC; saidencapsulating material having an opening therein adjacent the uppersurface portions of said IC to define an exposed portion of said IC; anda leadframe comprising a die pad carrying said IC, finger portions, anda plurality of die pad support bars extending between said die pad andsaid finger portions, each of said die pad support bars beingresiliently deformed.
 29. An integrated circuit package according toclaim 28 wherein said die pad is downset below a level of said fingerportions.
 30. An integrated circuit package according to claim 29further comprising bond wires extending between said IC and the fingerportion having a desired clearance from adjacent portions of said IC andan upper surface of said encapsulating material.
 31. An integratedcircuit package according to claim 28 wherein said die pad has anopening therein.
 32. An integrated circuit package according to claim 31further comprising a low stress, low modulus adhesive securing said ICto said die pad.
 33. An integrated circuit package according to claim 28wherein said encapsulating material comprises a low stress encapsulatingmaterial.
 34. An integrated circuit package according to claim 28further comprising vestigial portions of encapsulating material on theexposed portion of said IC and spaced inwardly from a periphery of theopening in said encapsulating material.
 35. An integrated circuitpackage according to claim 34 wherein the opening in said encapsulatingmaterial is generally rectangular; and wherein said vestigial portionsof encapsulating material are arranged along an imaginary rectanglespaced inwardly from the generally rectangular opening in saidencapsulating material.
 36. An integrated circuit package according toclaim 34 wherein said vestigial portions are spaced inwardly a distanceof from 0.1 to 3 mm.
 37. An integrated circuit package according toclaim 28 wherein the active devices define a sensor.
 38. An integratedcircuit package according to claim 28 wherein the active devices definean electric field fingerprint sensor.
 39. An integrated circuit packagecomprising: an integrated circuit (IC) comprising upper surface portionswith active devices formed therein and encapsulating materialsurrounding said IC; said encapsulating material having an openingtherein adjacent the upper surface portions of said IC to define anexposed portion of said IC; and a die pad carrying said IC, said die padhaving an opening therein.
 40. An integrated circuit package accordingto claim 39 further comprising finger portions, and a plurality of diepad support bars extending between said die pad and said fingerportions, and wherein said die pad is downset below a level of saidfinger portions.
 41. An integrated circuit package according to claim 40wherein each of said die pad support bars is resilient deformed toaccommodate the downset of said die pad.
 42. An integrated circuitpackage according to claim 40 further comprising bond wires extendingbetween said IC and the finger portion having a desired clearance fromadjacent portions of said IC and an upper surface of said encapsulatingmaterial.
 43. An integrated circuit package according to claim 39further comprising a low stress, low modulus adhesive securing said ICto said die pad.
 44. An integrated circuit package according to claim 39wherein said encapsulating material comprises a low stress encapsulatingmaterial.
 45. An integrated circuit package according to claim 39further comprising vestigial portions of encapsulating material on theexposed portion of said IC and spaced inwardly from a periphery of theopening in said encapsulating material.
 46. An integrated circuitpackage according to claim 45 wherein the opening in said encapsulatingmaterial is generally rectangular; and wherein said vestigial portionsof encapsulating material are arranged along an imaginary rectanglespaced inwardly from the generally rectangular opening in saidencapsulating material.
 47. An integrated circuit package according toclaim 45 wherein said vestigial portions are spaced inwardly a distanceof from 0.1 to 3 mm.
 48. An integrated circuit package according toclaim 39 wherein the active devices define a sensor.
 49. An integratedcircuit package according to claim 39 wherein the active devices definean electric field fingerprint sensor.
 50. An integrated circuit packagecomprising: an integrated circuit (IC) and encapsulating materialsurrounding said IC; said encapsulating material having an openingtherein to define an exposed portion of said IC; and a substratecovering a back surface of said IC opposite the exposed portion so thatsaid encapsulating material does not extend onto the back surface ofsaid IC.
 51. An integrated circuit package according to claim 50 whereinsaid substrate comprises a printed circuit board.
 52. An integratedcircuit package according to claim 50 further vestigial portions ofencapsulating material on the exposed portion of said IC and spacedinwardly from a periphery of the opening in said encapsulating material.53. An integrated circuit package according to claim 52 wherein theopening in said encapsulating material is generally rectangular; andwherein said vestigial portions of encapsulating material are arrangedalong at least one side of an imaginary rectangle spaced inwardly fromthe generally rectangular opening in said encapsulating material.
 54. Anintegrated circuit package according to claim 52 wherein said vestigialportions are spaced inwardly a distance of from 0.1 to 3 mm.
 55. Anintegrated circuit package according to claim 52 wherein saidencapsulating material comprises a low stress encapsulating material.56. An integrated circuit package according to claim 52 wherein said ICcomprises upper surface portions with active devices formed therein; andwherein the exposed portion of said IC comprises upper surface portionsthereof.
 57. An integrated circuit package according to claim 56 whereinthe active devices define a sensor.
 58. An integrated circuit packageaccording to claim 57 wherein the active devices define an electricfield fingerprint sensor.